Should I peel vegetables or leave the skin on?

The nutritional argument for keeping skins on is real but modest — the fibre and some nutrients are concentrated near the surface, and you lose a little by peeling. The texture argument is bigger and it points different ways for different vegetables, which is why there is no single rule worth following.

Step by step

1. Ask what the skin will do to the finished dish.Will it soften completely, or will it stay as a distinguishable layer? Butternut skin softens entirely when roasted and is unnoticeable; swede skin never softens and is unpleasant. That single question answers most cases.
2. Leave it on where it softens or adds texture.Carrots and parsnips (scrub well), new and salad potatoes, courgettes, aubergine, peppers in most dishes, butternut and other squash when roasted in wedges, tomatoes in a long-cooked sauce, mushrooms always. In these the skin either disappears or contributes.
3. Take it off where it is tough, waxed, bitter or in the way.Swede, celeriac, turnip, large old potatoes destined for mash, thick asparagus stems, squash for a velvety soup, broad beans if you want them bright green, garlic and onions obviously. Waxed swedes and cucumbers, and anything with damaged or green skin, come off too.
4. Cook first and peel afterwards where it is easier.Beetroot is far easier to peel cooked than raw and it holds its colour better. Tomatoes and peaches peel in seconds after a brief scald. Peppers peel after blistering under a grill. Jacket potatoes peel themselves in the eating.
5. Wash properly if you are keeping the skin.A firm scrub under cold running water with a brush does more than a rinse. It removes soil, most surface residue and any waxing on the vegetables that carry it. Peeling is a more effective route to a spotless surface, which is one honest argument for it.
6. Peel where appearance genuinely matters.A smooth pale purée, a fine dice for a garnish, a dinner-party gratin. This is a legitimate reason on its own and there is no need to justify it nutritionally.
7. Use the peelings.Onion skins, carrot and parsnip peelings, celery leaves, leek tops and mushroom stalks all go into stock. Potato peelings tossed in oil and roasted at 200°C for 15 minutes make a genuinely good snack.

Tips

• A speed peeler takes a thinner layer than a knife, so if you do peel, you waste less with the right tool.
• Organic and non-organic makes less difference here than people expect — washing removes most surface residue either way, and peeling removes it entirely regardless of how it was grown.
• Green potato skin is the one hard case: green means solanine and it should be cut away generously, or the potato discarded if the greening is extensive.
• Peeled vegetables dry out and discolour faster. If you peel ahead, keep them in cold water or a sealed container.

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